1. Field of the Invention
This invention relates generally to a system for eliminating unwanted light reflections within the cockpit of a vehicle having a canopy with a reflective interior surface and, more particularly, those light reflections which interfere with the ability to read information presented on a lighted display.
2. Discussion of the Prior Art
Over the years, there have been numerous attempts, many successful, for improving the ability, for example, of a pilot or other crew member of an aircraft to read displays presenting information of interest to the pilot or crew member. Throughout the instant disclosure, the terms "cockpit", "canopy" and "aircraft" are intended to refer more broadly to any vehicle with a substantially enclosed region in which an occupant has need to read displays, instrumentation, and the like, without interference from reflections, as from internal surfaces of the enclosed region, wherever they are located. Furthermore, the term "lighted display" is intended to mean any distinct display of intelligent information, whether lighted or not.
The following are typical patented devices and systems which are known to the inventor and which relate generally to the field of the present invention.
Head-up display systems which project an image of information onto a combining plate in the field of view of a pilot to permit the pilot to view the information while continuing to view the terrain over which he is flying have long been known and are disclosed, for example, in U.S. Pat. Nos. 4,592,620 to Poole and U.S. Pat. No. 3,915,548 to Opittek et al.
U.S. Pat. No. 4,723,160 to Connelly discloses a system for improving upon symbol position error due to windscreen angular deviation in a head-up display.
In this regard, each of the U.S. Pat. No. 4,776,692 to Kalawsky and U.S. Pat. No. 4,310,242 to Genco discloses a system for testing the optical quality of a light transmitting article, for example, an aircraft cockpit canopy.
Also, U.S. Pat. No. 5,057,744 issued Oct. 15, 1991 to Barbier et al. discloses a system for improving the readability of displayed information by adjusting for fluctuations in the light environment.
Each of the U.S. Pat. No. 5,128,678 to Novak et al. and to U.S. Pat. No. 3,897,033 to Harding et al. generally discloses a detection avoidance system which provides optimum visibility through a canopy of an aircraft cockpit. The former patent relates to minimizing microwave energy reflection and the later patent to sunlight reflection.
While U.S. Pat. No. 5,264,916 issued to Bushman discloses apparatus including a polarizer for detecting distant objects, each of the following U.S. patents discloses filter apparatus including, in each instance, a polarizing filter for improving visibility of an instrument mounted in a vehicle, for example, an aircraft: U.S. Pat. No. 5,200,844 to Suvada; U.S. Pat. No. 4,515,442 to Aron; U.S. Pat. No. 4,418,377 to Tamura, U.S. Pat. No. 4,328,532 Smith, and U.S. Pat. No. 3,760,215 to Sach. It is noteworthy that Suvada utilizes a pair of polarizing filters, although not for the purpose with which the present invention is concerned.